Results 5 issues of Jan Funke

As @clbarnes noted [here](https://github.com/funkey/gunpowder/pull/29#issuecomment-372806884), user-set attributes that refer to coordinates (like `resolution` or `offset`) will end up with different axis orderings depending on which implementation was used. A `z5` user...

DenoiSeg requires `keras` 2.2.5 (as per README instructions, but also during `pip install denoiseg`). This version of `keras` contains a workaround for a specific `h5py` version, where dataset attributes are...

- [ ] include keras as external module (similar to `caffe`) - [ ] implement `keras.Train` - [ ] implement `keras.Process`

enhancement

- [x] `AddAffinities` - [x] `Chunk` - [ ] `DefectAugment` - [x] `DvidSource` - [x] `ElasticAugment` - [ ] `ExcludeLabels` - [ ] `GrowBoundary` - [x] `Hdf5Source` - [ ]...

This PR adds `Lines` and `Text` annotations to spimagine, similar to how `Mesh`es are added. ![spimagine](https://user-images.githubusercontent.com/776708/52970301-5a485b80-3381-11e9-9515-d55a65c3cea2.png)